US President Donald Trump recently signed an executive order to begin building a 20 foot wall along the entire Mexican border. He also said that Mexico would be paying for this wall, although he did not specify how he planned to make Mexico pay.
In a tweet that he sent out later in the day, he said that if Mexico did not intend to pay for the wall, the Mexican President should stay at home and not plan to meet him. This forced the Mexican President Enrique Pena Nieto to cancel his trip to the US. He made this announcement on Twitter. Aides to President Trump have said that they would consider imposing a 20% import duty on all goods made in Mexico to collect money that they spend on building the wall.
President Trump and President Nieto were to meet to discuss the renegotiation of the North American Free Trade Agreement (NAFTA), which President Trump believes is responsible for American factories moving to Mexico. He thus intends to tax all goods manufactured in Mexic. He has also threatened to hurt the interests of companies that shut down factories in America and shift them to Mexico.
President Trump has been saying these things since he started campaigning to become the President of the United States of America. He had promised to build a wall along the Mexican border and make Mexico pay for it. It was a major campaign promise that he made.